To overcome the disadvantages experienced in the calibration of mass standards employing conventional mechanical balances, it has been proposed to use a strain gauge load cell which produces an electric signal in proportion to the force exerted on the cell. Typically, a plurality of strain gauges are located in the cell and are internally connected in the form of a bridge circuit, the output of which is connected to electronic measuring and recording equipment. Where the electronic measuring circuit is comprised of a low noise, high stability electronic circuit, wide fluctuations at the output of the bridge circuit due to temperature drift is not only undesireable, but intolerable where difference measurements are made betwen a standard weight and a test weight.
Accordingly, the present invention is directed to an improved bridge circuit formed by the strain qauges located in the load cell of a load cell mass comparator. The bridge circuit is modified for use as a difference transducer by coupling a temperature compensating circuit between ends of strain gauges in adjacent arms of the bridge. The compensating circuit is located remotely from the load cell containing the strain gauges and is comprised of a pair of relatively low valued series connected low noise, drift free precision resistors, which are respectively shunted by relatively high valued resistive potentiometers which are used for balancing the bridge. One potentiometer additionally includes a series connected relatively high valued low noise, drift free precision resistor for providing a means for providing fine balance of the bridge, while the other potentiometer is used for providing coarse balance .